“In-loop” carbonylation—A simplified method for carbon-11 labelling of drugs and radioligands

Transition-metal mediated carbonylation with ¹¹C-labelled carbon monoxide ([¹¹C]CO) is a versatile method for introducing ¹¹C (t_1/2 = 20.3 min) into drugs and radioligands for subsequent use in positron emission tomography (PET). The aim of the current study was to perform the ¹¹C-carbonylation reaction on the interior surface of a stainless-steel loop used for high performance liquid chromatography (HPLC). In the experimental setup, cyclotron produced ¹¹C-labelled carbon dioxide ([¹¹C]CO₂) was converted to [¹¹C]CO by reduction over heated Molybdenum and swept into an HPLC loop pre-charged with the appropriate reaction mixture. Following a 5 min reaction, the radiochemical purity (RCP) and the trapping efficiency (TE) of the reaction mixture was determined. After optimization, [¹¹C]N-Benzylbenzamide was obtained in quantitative radiochemical yield (RCY) following a 5 min reaction at room temperature. The methodology was further applied to label [¹¹C]benzoic acid (RCP≥99%, TE>91%), [¹¹C]methyl benzoate (RCP≥99%, TE>93%) and [¹¹C]phthalide (RCP≥99%, TE>88%). A set of pharmaceuticals was finally radiolabelled using non-optimized conditions. Excellent yields were obtained for the histamine-3 receptor radioligand [¹¹C]AZ13198083, the oncology drug [¹¹C]olaparib and the dopamine D2 receptor radioligand [¹¹C]raclopride, whereas a moderate yield was observed for the high-affinity dopamine D2 receptor radioligand [¹¹C]FLB457. The presented “in-loop” process proved efficient for diverse ¹¹C-carbonylations, providing [¹¹C]amides, [¹¹C]esters and [¹¹C]carboxylic acids in moderate to excellent RCYs. Based on the advantages associated with performing the radiolabelling step as an integrated part of the purification system, this methodology may become a valuable addition to the toolbox of methodologies used for ¹¹C-carbonylation of drugs and radioligands for PET.     

Abasic site recognition in DNA as a new strategy to potentiate the action of anticancer alkylating drugs?

Inhibition of abasic site repair in the cell seems an attractive strategy to potentiate the action of antitumor DNA alkylating drugs. Molecules that bind specifically and strongly to the abasic site are possible candidates to achieve such inhibition. We explored this strategy by preparing molecule 4 that incorporates (1) an aminoacridine intercalator for DNA binding, (2) an adenine moiety for abasic site recognition, and (3) a linker containing two guanidinium functions to increase binding to DNA without inducing cleavage at the base-sensitive abasic site. Compound 4 was compared to analogues containing secondary amines, i.e., 1. We report on synthesis of the new heterodimer 4. We show by physicochemical studies-including determination of association constants with calf-thymus DNA, T(m) measurements, and high-field NMR examination of the complexes formed with abasic DNA duplexes-that 4 binds specifically and more strongly to the abasic site than the analogues. Compound 4 does not cleave abasic plasmid DNA. Compound 4 shows apparent synergy with the anticancer bischloroethylnitrosourea (BCNU) in L1210 and A549 cell lines in vitro. It potentiates BCNU in the in vivo tests. The results favor the pertinence of the strategy.     

AMPA receptor antagonists with additional mechanisms of action: new opportunities for neuroprotective drugs?

Ischaemic stroke of the brain accounts for about one third of all deaths in industrialized countries. Many of the patients who survive are severily impaired. Thus, there is an enormous need for pharmacotherapy for the treatment of ischaemic stroke. Why is such a treatment not available yet? Are the pathophysiological sequelae of brain ischaemia not well understood? Have there been no attempts for clinical development of neuroprotective drugs? Everyone who is engaged in stroke research knows that the opposite is true: The cellular processes occuring after brain ischaemia have been studied for a long time, and we have a thorough understanding of the cellular processes which are involved. Many compounds underwent clinical trials, but most of them failed. One hypothesis to explain this disappointing fact might be that the cellular consequences of stroke are manyfold, but that the clinically tested compounds were selective for only one molecular mechanism. The aim of this review is to give a summary of the pathophysiological mechanisms which occur during and after an ischaemic stroke, and to comment on the preclinical studies where multiple disease-related mechanisms were targeted pharmacologically. Moreover, a novel class of neuroprotective compounds, the oxadiazole derivatives, will be presented. Compounds of this chemical class target two key mechanisms which are important for the pathophysiology of stroke, namely voltage-gated sodium channels, as well as glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype.     

Electrointraperitoneography: A new method for testing the pharmacological effects of drugs at the intestine level—Preliminary note

A recent and nontraumatizing method, electrointraperitoneography (EIG), has been used in the anesthetized rat in order to test its usefulness for the pharmacological study of drug effects on the electrical activity of the intestine. The results show that such a study is possible for different drugs. Advantages and disadvantages of the method are discussed.     

Stability of drugs of abuse in synthetic oral fluid investigated using a simple “dilute and inject” method of analysis

Human oral fluid is well established as a matrix for drug screening, particularly in the workplace. The need to synthesise synthetic oral fluid (SOF) has been recognised in order to overcome human oral fluid's composition variability. We have used SOF spiked with six common drugs of abuse or their primary metabolites: morphine, amfetamine, benzoylecgonine, cocaine, diazepam, and (−)-Δ⁹-tetrahydrocannabinol (THC) in order to assess the suitability of this matrix for quality assurance purposes. For confirmation of a drug screening test, controls and spiked standards are normally required. All our analytes were detected by LC–MS/MS using a quick and easy “dilute and inject” sample preparation approach as opposed to relatively slower solid-phase extraction. The limit of detection (LOD) was 10 ng/ml for diazepam and THC and 5 ng/ml for morphine, amfetamine, benzoylecgonine and cocaine. Validation results showed good accuracy as well as inter- and intra-assay precision (CV [%] < 5). Our work highlighted the importance of adding Tween® 20 to the SOF and calibrants to reduce losses when handling THC. Furthermore, drug stability was tested at various temperatures (5°C, 20°C and 40°C), for a number of days or after freeze–thaw cycles. Recommendations regarding storage are provided, the spiked SOF being stable at 5°C for up to 1 week without significant drug concentration loss.     

Cardiovascular ATP-sensitive K~ channel as a new molecular target for development of antihypertensive drugs

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Last generation of amino-bisphosphonates (N-BPs) and cancer angio-genesis: a new role for these drugs?

Bisphosphonate (BPs) therapy has become a standard of care for patients with malignant bone disease. In addition, preclinical and preliminary clinical data suggest that BPs exert their direct or indirect antitumoral effects on cancer growth factor release, on cancer cell adhesion, invasion and viability, on cancer angiogenesis and on cancer cell apoptosis. Here, after a brief analysis on clinical indications, on the last generation amino-bisphosphonates (N-BP) and on biochemical pathways as molecular targets of BPs, we will discuss the molecular mechanisms of these antitumor effects. Recent evidence suggests that part of the antitumor activity of bisphosphonates may be attributed to an antiangiogenic effect. For this reason, we will analyse all the in vitro and in vivo preclinical reports and the first clinical evidence of anti-angiogenic activity exerted by this class of drugs. Several patents have been reported in the review, considering the recents activities observed for these drugs. Taking together all the major results obtained in the described studies, it is possible to affirm that BPs, particularly zoledronic acid and pamidronate, could potentially represent a very powerful tool for angiogenesis inhibition leading to a better control of cancer growth and progression. The translation into the clinical setting of the preclinical evidence of an antiangiogenic power of these drugs is becoming an imperative need and should represent the objective of future clinical trials.     

Azole antimycotics--a highway to new drugs or a dead end?

Azole antimycotics are a well-known and important class of agents that are used in hospital practice, everyday health care, veterinary medicine and for crop protection. The era of azole fungicides began with the breakthrough of chlormidazole roughly 50 years ago. Since then, more than 20 drugs of this group, including triazoles, have been brought to the market. The specific chemical structure and mechanism of the action of azoles along with the eukaryotic character of fungal pathogens raise several serious issues. Resistance to drugs and disturbance to metabolic pathways are among the most important. On the other hand, these same features are responsible for unique and novel applications of these drugs. As a result, old and ineffective antifungal drugs can be successfully used in the treatment of parasitic diseases, bacterial infections or cancers. Are azoles getting their second wind?     

Toxicity of ingredients in artificial tears and ophthalmic drugs in a cell attachment and spreading test†

Abstract

During re-epithelialization of corneal erosions, the epithelial cells are attached and migrate on a fibronectin-containing substratum. In earlier studies we found that topical application of the plasmin inhibitor aprotinin promoted healing of corneal epithelial defects, presumably inhibiting proteolytic degradation of fibronectin and related adhesive proteins. The present study investigated, using an in vitro cell culture test, the action of various ophthalmic preparations on cell attachment and spreading on a fibronectin-coated substratum. The cell culture test was designed to simulate the situation in the wounded corneal epithelium in vivo. Analysis of 16 different ophthalmic preparations indicated that the toxicity of some of them in the test could be assigned to specific ingredients (benzalkonium chloride, thimerosal sodium, Tween 80) used as additives. In contrast, chlorobutanol, used widely as a preservative, was nontoxic in the test, in concentrations used in ophthalmic preparations. It should be noted that the wounded and inflamed cornea may be more vulnerable to the toxicity of topical mediations than an intact corneal epithelium. hoper tests of the vehicle are therefore recommended before clinical trials are undertaken.     

HIV entry inhibitors： a new generation of antiretroviral drugs

AIDS is presently treatable, and patients can have a good prognosis due to the success of highly active antiretroviral therapy (HAART), but it is still not curable or preventable. High toxicity of HAART, and the emergence of drug resistance add to the imperative to continue research into new strategies and interventions. Considerable progress in the understanding of HIV attachment and entry into host cells has suggested new possibilities for rationally designing agents that interfere with this process. The approval and introduction of the fusion inhibitor enfuvirtide (Fuzeon) for clinical use signals a new era in AIDS therapeutics. Here we review the crucial steps the virus uses to achieve cell entry, which merit attention as potential targets, and the compounds at pre-clinical and clinical development stages, reported to effectively inhibit cell entry.     

A new biological test of water toxicity–yeast Saccharomyces cerevisiae conductometric test

This new biological test of water toxicity is based on monitoring of specific conductivity changes of yeast Saccharomyces cerevisiae suspension as a result of yeast fermentation activity inhibition in toxic conditions. The test was verified on ten substances with various mechanisms of toxic effect and the results were compared with two standard toxicity tests based on Daphnia magna mobility inhibition (EN ISO 6341) and Vibrio fischeri bioluminescence inhibition (EN ISO 11348-2) and with the results of the S. cerevisiae lethal test (Rumlova and Dolezalova, 2012). The new biological test – S. cerevisiae conductometric test – is an express method developed primarily for field conditions. It is applicable in case of need of immediate information about water toxicity. Fast completion is an advantage of this test (time necessary for test completion is about 60 min), the test is simple and the test organism – dried instant yeast – belongs among its biggest advantages because of its long-term storage life and broad availability.     

Kynurenic acid: a new effector of valproate action?

We investigated the changes in hippocampal kynurenic acid (KYNA) concentrations and the amino acids involved in neuronal activity regulation following valproate (VPA) administration (400 mg/kg ip) in pentylenetetrazole-kindled rats (in vivo). We found a remarkably long-lasting increase in KYNA levels following VPA administration, and this effect correlated with a rise in GABA levels. No changes in the concentration of other analyzed amino acids were present. It is likely that the antiepileptic and neuroprotective properties of VPA may also be a consequence of an increase in the hippocampal KYNA concentration.     

Relevance of a “Dear Doctor letter” to alert healthcare providers to new recommendations for vitamin D administration

Purpose  

After reports of malaise in infants immediately after the oral administration of two brands of vitamin D solutions, a “Dear Doctor letter” (DDL) containing recommendations for the administration of vitamin D was sent to all French paediatricians and pharmacies and a large number of French general practitioners (GPs) with a predominantly paediatric practice. The DDL and a press release were published on the French Medicines Agency website and distributed via a mailing list. The objective of this study was to assess the effectiveness of such a DDL and to collect the opinions of healthcare professionals on the best way to provide them with information.